Transfer element containing infrared radiation absorbing material



United States Patent F U.S. Cl. 11736.1 6 Claims ABSTRACT OF THE DISCLOSURE Transfer elements of the squeeze-out type comprising a porous resin structure containing pressure-exudable ink within the pores thereof. The ink comprises an oleaginous vehicle and coloring matter and the vehicle is rendered infrared radiation-absorbing by having dissolved therein an infrared radiation-absorbing chemical.

The so-called waxless carbon papers are enjoying widespread commercial success and are rendering the conventional hot melt wax carbon papers obsolete for a number of dilferent uses. The waxless carbon papers are based upon resinous binder materials applied bv means of volatile organic solvents, the resinous binder forming a continuous, porous, non-transferable network which includes pressure-exudable ink as the discontinuous phase. The ink comprises a non-volatile, fiowable vehicle which is incompatible with the resinous binder and which includes an amount of coloring matter such as dispersed pigment or dissolved dyestutf.

Such waxless carbon papers are reusable many times and function by exuding a small amount of ink each time pressure is applied thereto. Unlike the hot-melt wax carbon papers, the waxless carbon layers are not frangible and do not transfer a solid mass of imaging matter to the copy sheet. The waxless carbons transfer only a fluid ink to each copy sheet so that the images formed thereon are actually little more than ink stains. Such stains contain little coloring matter and thus are generally much weaker in density than the solid images produced by wax carbons. This is particularly true of waxless carbons which have been reused many times.

One of the most important problems resulting from the low pigment concentration of the images produced with a waxless carbon paper or ribbon is the inability to reliably produce legible thermographic copies thereof. Attempts to overcome this problem by including larger amounts of pigment such as carbon black, or by using pigments such as graphite having high infrared radiationabsorbing qualities, have not been completely successful since the amount of pigment which can be exuded to a copy sheet after the carbon sheet or ribbon has been reused repeatedly remains relatively low, and since the incorporation of excess pigment results in a carbon paper having non-uniform wear characteristics. The initial images are excessively dark and dirty to the touch and the imaging strength of the carbon paper gradually lightens with use.

It is the object of this invention to overcome the aforementioned difliculties and to provide a waxless carbon paper or ribbon which produces duplicate images of uniform tone or density which may be reliably thermographically-reproduced throughout the effective life span of the carbon paper or ribbon.

This and other objects and advantages of this invention will be clear to those skilled in the art in the light of the present disclosure.

The present invention is based upon the discovery that previous attempts to improve the infrared radiation-ab- 3,446,662 Patented May 27, 1969 sorbing properties of images produced with waxless carbons were misdirected in that I have discovered that it is impossible to produce this result over the life span of the carbon by using only solid additives having high infrared radiation-absorbing properties. My invention resides in the discovery that this result can be accomplished by using an infrared radiation-absorbing material which is soluble in the ink vehicle and is used at least primarily in the dissolved state. In effect, the dissolved portion of the infrared radiation-absorbing material converts the ink vehicle to an infrared radiation-absorbing vehicle so that the images produced therewith are capable of thermographic reproduction for as long as the present carbon papers and ribbons are capable of exuding ink under the effects of imaging pressure.

Secondly, where the infrared radiation-absorbing material is used in completely dissolved condition, it does not interfere with the amount of pigment which can be used, or with the uniformity of the tone of the duplicate images over the life span of the carbon paper or ribbon.

The waxless carbon papers and ribbons which may be modified according to the present invention are those of the conventional type based upon a synthetic resinous binder material, a fiowable ink vehicle which is incompatible with the binder material, an amount of pigment or dyestuff dissolved or dispersed in the ink vehicle, and an amount of filler or extender, if desired, the ink layer being applied as a solution of the binder material in one or more volatile solvents. Suitable compositions which may be modified according to this invention, and the methods of making the same and the methods of applying the same to a flexible foundation to form carbon papers and ribbons are as illustrated by the following United States patents, the disclosures of which are incorporated herein and made a part of the present dis closure: Nos. 2,820,171, 2,984,582, 3,037,879, 2,944,037, and 3,117,018. The fiowable ink vehicle may contain semi-solid oleaginous materials such as lanolin, petrolatum and the like, as taught by aforementioned US. Patent No. 2,984,582, which reduce but do not destroy the pressure-fiowability of the ink.

The infrared radiation-absorbing additives suitable for use according to the present invention are of the oilsoluble type since the ink vehicles are generally classified as oleaginous materials. However, in many cases the oilsolubility of these additives is quite low. This is unimportant provided that the solubility level is sufficiently high to permit the dissolution of at least a small amount of the additive. In most cases the amount of dissolved additive will range from about 1% by weight up to about 10% by weight based upon the weight of the ink vehicle. Where the amount of dissolved additive is low due to poor solubility in the oil phase, then it is necessary that the additive is soluble in the volatile organic solvent used to apply the transfer composition to the foundation sheet. In this way, the pigments or fillers, which eventually are present in the oily ink phase, become coated and/or impregnated with the additive and the additive is deposited thereon and/or therein when the volatile solvent is evaporated. In this manner, the total amount of additive transferred to the copy sheet is certain to be suificient to produce the desired result.

The preferred infrared radiation-absorbing additives used according to this invention are aminophenylaminium salts having the following chemical structure:

wherein Y equals a total of three similar or different radicals having the structure shown, R and R are the same or different lower alkyl groups having from 1 to 5 carbon atoms, preferably methyl and ethyl groups, or are p-dialkylaminophenyl radicals in which the alkyl groups contain from 1 to 5 carbon atoms and are preferably methyl and ethyl groups, and X is an anion of a strong acid such as picrate, benzenesulfonate, perchlorate, hexafiuoroantimonate, fiuoroborate, trichloracetate, hexafluoroarsenate, or the like.

Other suitable infrared radiation-absorbing additives are the his (p-aminophenyl) vinylcarbonium compounds of US. Patent No. 2,813,802; the manganese complexes of o-nitrosohydroxy aromatic compounds disclosed in US. Patent No. 2,971,921; the salts of 9-phenyl fluoren-9-ol disclosed in US. Patent No. 3,000,833.

Of course it should be understood that not every additive can be included in any of the waxless compositions contemplated. The additive must be included in an ink vehicle in which it has the required degree of solubility, and such ink vehicle must be used with a resinous binder material with which it has the required degree of incompatibility to provide a squeeze-out action waxless carbon paper or ribbon. The additive is preferably soluble in the volatile coating solvent to assist dissolution in the oil phase, the oil also being soluble in the coating solvent.

The following examples are illustrative of the production of a waxless transfer element of the type contemplated by the present invention and are set forth only as illustrative and not limitative:

Example 1 Ingredients: Parts by wt. Vinyl chloride-vinyl acetate copolymer (Vinylite VYHH) 10 Oleic acid 12 Mineral oil 8 Lard oil 8 Toned carbon black 3 Alkali blue 2 Infrared radiation-absorber I 2 Toluol 15 Ethyl acetate 45 Example 2 Ingredients: Parts by wt. Polystrene 10 Castor oil 10 Oleic acid 5 Toned carbon black 3 Alkali blue 2 Clay 10 Infrared radiation-absorber II 2 Methylene chloride 70 Example 3 Ingredients: Parts by wt. Vinyl chloride-vinyl acetate copolymer 7 Methyl methacrylate 10 Polystyrene 2 Dioctyl phthalate 2 Castor oil Oleic acid 2 Alkali blue 10 Toned carbon black 6 Infrared radiation-absorber I 3 Toluol 1O Methyl ethyl ketone 60 The compositions of the foregoing examples are applied to any flexible foundation sheet such as paper or plastic film and the volatile solvents are evaporated to form inkreleasing sheets and/or ribbons in conventional manner. However, the infrared radiation-absorber is preferably predissolved, at least to some extent, in the ink vehicle.

The infrared radiation-absonbers of the examples are identified as follows:

Infrared radiation-absorber I is p-[bis (p-diethylamino- 4 phenyl) amino] phenyl bis (p-diethylaminophenyl) aminium hexafluoroantimonate and has the structure:

Infrared radiation-absorber II is tris (p-diethylaminophenyl) aminium fluoroborate and has the structure:

A number of oleaginous materials which have the required solvent power for the infrared radiation-absorbing additives also exhibit some solvent or plasticizing properties for a number of the resinous binder materials if used in sufiiciently high amounts. In such cases it has been found possible to use non-plasticizing amounts of such oleaginous materials containing the dissolved additive in admixture with larger amounts of the more conventional non-plasticizing oleaginous ink vehicles such as the animal, vegetable and mineral oils with which they are compatible and which need not be solvents for the infrared radiation-absorbing additive.

Illustrative of oleaginous materials which dissolve sufficient amounts of the present infrared radiation-absorbers are heterocyclic compounds such as tetrahydrofuran, organic esters such as dibutyl phthalate, dioctyl phthalate and tricresyl phosphate, organic ethers and alcohols such as ethylene glycol monoethyl ether and propylene glycol, fatty acids such as oleic acid, fatty acid esters such as found in castor oil, fatty alcohols such as oleyl alcohol, and the like. The oleaginous material must be a sufficiently good solvent for the additive so that the amount of dissolved additive equals the required amount of from about 1% up to about 10% based upon the total weight of the oily ink vehicle. On the low end of this range, 1% to 4%, it is preferred to have an additional 4% to 1% of undissolved additive present in or on the pigment, as discussed supra.

Images produced with the carbon papers and ribbons of the present invention are thermographically-reproducible by means of any of the known infrared radiation processes. One such process employs heat-reactive copy sheets commercially available under the registered trademark Thermo-Fax. Such copy sheets form duplicates of the present images by means of heat-reaction in areas corresponding to the location of the present images on an original sheet. Another process employs heat-transfer sheets commercially available under the registered trademark Transofax. Such sheets transfer imaging composition to a separate copy sheet under the effects of heat generated by the present images exposed to infrared radiation. A number of other infrared radiation copying processes may also be used, as will be obvious to those skilled in the art.

I claim:

1. A pressure-sensitive transfer element adapted for the placing of images which are thermographically-reproducible by means of infrared radiation, comprising a substantially non-transferable synthetic resinous binder material having dispersed therein a pressure-exudable ink comprising a pressure-flowable oleaginous vehicle which is incompatible with said binder material and an amount of coloring matter, characterized by the fact that from about 1% to 10% of an infrared radiation-absorbing material selected from the group consisting of amino phenyl aminium salts, bis (p-amino phenyl) vinyl carbonium compounds, manganese complexes of o-nitrosohydroxy aromatic compounds and salts of 9-phenyl fluoren-9-ol, based upon the weight of the oleaginous vehicle, is present in dissolved condition in said oleaginous vehicle.

2. A pressure-sensitive transfer element according to claim 1 in which the binder material comprises a vinyl resin and the oleaginous vehicle comprises a liquid oil.

3, A pressure-sensitive transfer element according to claim 1 in which the infrared radiation-absorbing material comprises an amino phenyl aminium salt having the wherein Y equals a total of three similar or different radicals having the structure shown, R and R are selected from the group consisting of the same or different lower alkyl groups having from 1 to 5 carbon atoms, and pdialkylaminophenyl groups having from 1 to 5 carbon atoms in the alkyl groups, and X- is an anion.

4. A pressure-sensitive transfer element according to claim 3 in which the infrared radiation-absorbing material comprises p-[bis (p-diethylaminophenyl) amino] phenyl bis (p-diethylaminophenyl) aminium hexafiuoroantimonate.

5. A pressure-sensitive transfer element according to claim 3 in Which the infrared radiation-absorbing material comprises tris (p-diethylaminophenyl) aminium fluoroborate.

6. A pressure-sensitive transfer element according to claim 3 comprising a vinyl resin binder material, an

oleaginous ink vehicle selected from the group consisting of fatty acids, fatty acid esters and fatty alcohols, coloring matter and an infrared radiation-absorbing material as defined by claim 3.

References Cited UNITED STATES PATENTS 2,813,802 11/1957 Ingle et al. 11733.3 2,992,121 7/1961 Francis et al. 11736.1 3,117,018 1/1964 Strauss 11736.1 3,207,621 9/1965 Newman et al 11736.1 3,287,153 11/1966 Schwarz et al. 11736.1 3,306,867 2/1967 Popiolek 11736.1 3,330,791 7/1967 Mater et al. 117-36.1 FOREIGN PATENTS 847,398 9/1960 Great Britain. 849,756 9/ 1960 Great Britain.

MURRAY KATZ, Primary Examiner.

U.S. Cl. X.R. 1l7-155; 26041 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,446,662 May 27, 1969 Douglas A. Newman It is certified that error appears in the above identified patent and that said Letters Patent are hereby corrected as shown below:

Column 2, line 36, "2,820,171" should read 2,820,717 same column 2, lines 65 to 70, the subscript "y" outside the parenthesis should read Signed and sealed this 14th day of April 1970.

(SEAL) Attest:

WILLIAM E. SCHUYLER, JR.

Edward M. Fletcher, Jr.

Commissioner of Patents Attesting Officer 

